Furnace grate



1, 1931. E. B. PRIEQ'BE ET AL 1,833,952

FURNACE GRATE Original Filed Jurie 25, 1921 s Sheets-Sheet 1 Dec. 1,1931. B. PRIEBE ET AL FURNACE GRATE Original Filed June 25, 1921 3Sheets-Sheet 2 M243 &CM

Dec. 1, 1931. E. B. PRIEBE ET AL 1,833,952.

I FURNACE GRATE I Original F'iled June 25, 1921 3 Sheets-Sheet 3 3wve'wtoag W k 9mm T. W %11 duo M42135 ra mmd KMWI.

Patented Dec. 1, 1931 UNITED STATES ERNEST B. PRIEBE, OF RICHMOND HILL,

NEW" YORK, AND DANIEL r. MINER, or

PROVIDENCE, RHODE ISLAND, ASSIGNORS, BY DIRECT AND MESNE ASSIGNMENTS, T0FURNACE ENGINEERING COMPANSLINQ, OF NEW YORK, N; Y., CORPORATION 5 if OFNEW YORK FURNACE GRATE 7 Original application filed June 25, 1921,Serial No. 480,394. Divided and this application filed Apri14,

1927. Serial no. 181,014.

This invention is, a novel furnace grate adapted for use in connectionwith automatic stokers and being herein illustrated in connection withan underfeed stoker for aboiler furnace- The general objects of thepresent invention are to afford a furnace grate and stoker of greaterefliciency in operation and superior strength and durability inconstruction. A particular object is to minimize the difficulty of thesifting of ashes through the grate into the wind box, which has beenquite pronounced in certain types of stokers. Another object is toimprove the operation and efficiency of the furnace by perfecting themanner and means of air distribution. Another specific object is toafford a novel and advantageous system of twyers for afurnace grate.Other and further advantages of the present invention will be made toappear in the hereinafter following description of one form ofembodiment thereof or will be apparent to those skilled in the art.

To the accomplishment of the objectsand advantages mentioned the presentinvention consists in the novel furnace grate and stoker hereindescribed and illustrated and the novel features of arrangement,combination, construction and operation thereof.

In the accompanying drawings forming a part hereof Fig. 1 is alongitudinal section, taken on the line 11 of Fig. 2, of a furnace,stoker and grate embodying the principles of the present invention. r

Fig. 2 is a transverse section taken on the line 2-2 of Fig. 1, lookingtoward the rear or bridge wall of the furnace.

Fig. 3 is a perspective view showing the construction and arrangement ofthe different kinds of'members constituting the main grate.

Fig. 4 is a partial vertical section taken at or beneath the position ofthe line appearing on Fig. 3. r

This application is a division of our application for furnace grates,filed June 25, 1921, Serial No. 480,394, being based upona por tion ofthe original disclosure of said application, the same having nowresulted in United States Patent No. 1,633,418, granted June 21, 1927without containing the complete original disclosure. 4 Jv Although theinvention might be applied PATENT owes to furnaces, stokers and gratesof; various kinds and types we have'merelyshown the same applied to thekind .offurnace embodys ing what is known in the trade as a Type Estoker. The so-called Type E stoker is used more'especially for boilersof smaller sizes and usually there is but one retort to thefurnace,although we wishit understood that the single retort shown in Figs. 1and2 could be duplicated, or a number of retorts maintained beneath asingle boiler. Certainof the devices herein shown, including the stokeractuating mechanism in front of the furnace, are not herein claimed tobenovel, but indeed are well known constructions not requiring detaileddescription; for example, the

exemplified in the patent of Wood No. 818, Y

010 of April 17th, 1906.

Referring to the details of the herein illustrated embodiment of thepresent invention, the combustion chamber of; the furnace ,is shown asbounded by theusual wall 7 at the front, bridge wall 8 at the rear andside walls 9,9,and at the upper part of the combustion chamber isindicated a portion of a water tube boiler 10. The entire structure isshown resting upon concrete foundations 11 within which isprovided, foreach retort, --an' air duct -12 which serves to convey forced draft,

. controlled by damper 13, into the passage 14:

constitutingan air box directly bene'athth'e retort and supplying air tothe two opposite wind boxes beneath the grates, as will be described.

Above thegratesjisshown' the fuel bed'15 and while the present inventionmight be applied to a furnace'having a fuel bed maintained in differentways, for example, by overfeed, it is herein" shown maintained byunderfeed, as is customary with the illustrated type of grate. Anexterior fuel hopper 16 delivers fuel dir'ectly in front of areciprocating ram 17 which at each advance stroke thrusts a designatedamount of fuel into the lower part of the fuel bed in the furnace. Theram 17 is rigidly connected with a reciprocating crosshead 18 actuatedthrough a connecting rod. 19 by a piston 20 within" a cylinder-21"supplied with steam by a pipe 22, the operation of these parts beingregulatedby mechanism 23,. the details of V which are well known andform no partof the present invention.

' The 'fuel thrust into the furnace by the ram 17 passes through theexpandingthroat 24 into the retort 25. The fuel passes rearwardthrough:the length of-theretort and also piles up and spills over laterally atboth sides forming a symmetrical fuel bed, as shown in'Fig. 2, the fueltravelling down. the inclined grates at the two sides and finally,when'burnedout, being discharged bythe dumping grates 26 into the ashpits 27. The general course of the fuel having been thus explained theconstruction of the retort, the grates, the wind boxes and theaircontrol will now be described. r

The retort has its bottom formed by a plate'29 which as usual in thistype of fur nace is arranged to reciprocate rearwardl-y and forwardly,the side edges of the plate '29 -resting' upon ribs 30 formed on thewind fuel support-atian'd'tothe rear ofthe throat.

The ram 17 is rigidly; connected upon the plate 32 and therebyreceivesits reciprocat'ion. Th'erear extremity of the bottom plate 29 slidesbeneathan inclined plate 33 forming the. rear end' of the retort;

Iirthis symmetrical design of furnace the retort stands between twosimilar grates which are air supplied and which,therefore,

in efiect form theupper sidesoftwo opposite similarchambers or windboxes-r These will now be describedi Owin'g to'the preferred flaringshape of" the'retort 25" each-of the "wind boxes may be considered ashaving a ridgeor peak and two slopes,*an abrupt slope from the ridgeonthe retort side, comprisingtwyer members, and a more gradual slope orinclineat' the-outer side, constituting the ra v 'The inner side of eachwind box is' pref 'e'r'ablya vertical metal wall, the lower part of theretort.

ofw-hich forms a wall of-the airbox 14 and the upper' part 36 of fwhichforms a side wall Resting on the walls 36 are the-sloping twyer members37 consisting of up'standihg members in face contact, with grooved edgesaffording tapered apertures discharging" into the retort; twyer membersrest a series of cap plates'38 Above these which form the ridge or peakof the grate. At the other side of the cap plates extends at a downwardslant the main grate 39 at each side. The lower end of the gratesrest:

upon" bearing plates 41 at the right and left. Belowthe bearing platesare downwardly extending walls 453, and therebelow diagonal walls 14:connecting with the bottomwalls 455, which extend toward the center andare united with the first mentioned-upright wall portions bounding theair box.

Each wind box is shown with a partition 46 separating it into twochambers connected byan'opening controlledby a damper 470perated by anexternal handle 4-8. Each wall portion: 35: has a. sliding damper 49operable from. an-exterior'handle 50 through a slidingrod 51.v The:course of the air is thus through the main. airduct 12, the .air box 14,the dampers 49: into the wind box and partially'through the dampers 5L7and upwardly from the. windbox through all portions of the grate intothe fuel bedr The wind. box: construction is held steady and; rigid byits support and attachment upon aportion: of the concrete foundation ll.The upright wall 36 has attached to it'two or morethree-armed brackets53. Unearm of this'bracket is used. to secure in" place the twyermembers 37 by means of a rod 5r passe ing through the bracket arms andperfcrat ed extensions-f the twyers. Similarly" a second; arm of thebracket "is used togive support to the' stationary bars of the grate 39ort 40, a' rod 55 extending through the arms and extensionsof the bars.

The cap plates 38 are. of novel form seen. in all: the figures. Each capplate is beveled at its front end ivin an inclined.

overhang 59 which fits against a correspondbe' clear' from Fig. 1'; eprefer that the cap plate should be constructed with grooves 60 formingapertures at the undersides of the plates for'delivering'air laterallyin both directions, that is, into the retort and above the main' grate.The cap plates are also shown provided with ribs 61 which are arrangedlongitudinally,.these serving to divide "IDS mg incline of the adjacentcap plate as will the surface of the cap plates into concave P r areaswhich we find to be of substantial ad- This gives a decided protectionagainst the deterioration of the plates and substantially prolongs thelife of the cap plates. V The cap plates are shown locked and held inplace by means of dovetail extensions,

such as tofit between the inclined twyer members 37 and the, upper edgesof the stationary bars of the grates 39.

Coming'now'to-the main grates, each of these comprises aiseriesofinclined grate bars arranged adjacent to each other extending at rightangles to the length of the retorts and, of course, longitudinally tothe downward advancing travel of the fuel, which passes laterally fromthe retort toward the dumping grates near the opposite side Walls. Theseside by side grate bars are shown as stepped, that is each one of themis formed with a series of horizontal surfaces one beneath another sothat the advancing fuel bed passes downwardly step by step toward thedischarge. Alternate grate bars reciprocate longitudinally of thedirection of the fuel feed relatively to the remaining bars which arepreferably stationary or non-reciprocating. This construction is shownin front elevation in Fig. 2, which shows a stationary bar at the rightside and a reciprocating one at the left. Fig. 3 shows several adjacentbars in perspective, partly broken away, and Fig. 4: is a vertical crosssection of several of them. The alternate stationary grate bars 65 havethe movable grate bars between them and the two are of slightlydifferent construction for a purpose which will appear. Each stationarygrate bar has its topmost portion, which may be termed the top piece ortop step 66, of the combined width of two adjacent grate bars. Thus theentire top of this system of grate bars consists of stationary members65 and these are so shaped and arranged as to engage and lock with thedovetail of the cap pieces 38, already referred to.

The stationary grate bar 65, below its flat top step 66 is formed withintegral second, third, etc. steps 67 to 72, a total of 7, atsuccessively lower levels. The grate bar has a substantial verticaldimension below each step and this downward extension is provided withseveral horizontal ribs or tongues 7 3, extending to the right in Figs.3 and 4t, and 74: extending to the left, staggered or offset relativelyto the ribs 73. These ribs and the recesses between them are for thepurpose of engaging similar ribs and recesses on the reciprocating gratebars giving a com pact interfitting system, sufliciently loose fitting,however, to permit the forced draft of air to pass horizontally betweenthe grate bars for discharge into the fuel at each level of the grate.

Each of the movable grate bars 75 is formed with a top step 76. This isnot at the same level with the top sections of the stationary bars, butis accommodated between the latter and the uppermost rib 7 3, asclearlyshown in Figs. 8 and 4, the upper end of the movable bars thusreceiving support and guidance for their reciprocating movements. Thesucceeding lower steps 77, 78, etc. of the movable grate bars are thesame levels as the corresponding steps 67, 68, etc. of the stationarybars; and the depending portion below each step of the movable bar isprovided with ribs or flanges831and ribs 8a which partake in theinterengaging structure and function alreadymentioned. j 1

This construction of'grate gives very effective air supply to the fuelbed and yet is 1 i such as to practically prevent the possibility ofsiftings passinginto the wind boxes. The air outlets are horizontal andthere would be no tendency for ashes, etc. to pass inwardly toward theair supply. At the same time the air supply is ample and is delivered inan effective direction and with thorough distribution beneath the entirearea of the fuel bed. 3

-The reciprocating or ments of the grate bars 75 are effected through "aconnecting rod 85 actuated'by'a rock arm oscillating move- 86 or a rockshaft 87 which is worked auto- I matically under control of the timingmech- V anism 23. a l

The illustrated features of the present :invention, involving a certainamount I of looseness and play between the different grate bars,prevents any damage from expansion and contraction of the metal; thestructure has an elasticity orself yielding'quality which takes care ofthe difficulties frequently involved in the expansion of the metal. 7Another andvery important advantage of this V invention is theprotection of the grate bars by maintaining them relatively cool. Thisis a due to the mode of air travel, which passes horizontally throughthe spaces betweenthe inclined grate bars and therefore has an extendedlength of travel in contact with the plied more eficiently andcompletely than in a different arrangement, andthe heat which It willthus be seen that we have described a furnace grate embodying theprinciples and attaining the objects and advantages of the presentinvention, Since many matters of arrangement, combination; design anddetail may be variously modified without departing from the principlesinvolved, it is' not intended to limit the invention to such mattersexcept in so far asspecified in the appended claims. 7 i

What is claimed is:

1. In a furnace having a central fuel retort and a pair 'of oppositelyinclined grates one along eachof the lateral'sidesof the retort, theretort discharging laterally over such sides upon such grates, eachgrate composed of inclined gratebars (65, 75) having stepped fuelsupporting top sides, loosely interfitting to afford narrow air passagesdelivering into the fuel bed, and alternate grate bars (65) beingstationary and having wide topmost portions alined longitudinally with-metal. The cooling effect is therefore apis produced at the outersurface of the grate 1,

ins

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'respect to the retort, the remaining bars (7 5) being movable andterminating short of such topmost portions, and connections formethodically reciprocating'the movable bars.

2.-In a furnace havlng a central fuel retort and a pair of. oppositelyinclined grates one along each of the lateral sides of the retort, theretort discharging laterally over suchsidesupon such grates, each gratecom- 7 posed of alternating inclined grate bars 'of two shapes eachhaving fuel supporting steps, the grate bars'of one shape having widetop portions in horizontal longitudinal alinement with respect to theretort,and those of 1 5 the other shape terminating below such alinedportions, and means for reciprocating the bars of'one shape relativelyto those of i the other.

3. A furnace as'in claim 2 and wherein are cap plates extending acrossfrom the tops of the retort sides tothe top portions of the grate barsof'the first shape and interlocked therewith.

4. In a furnace having a centralfuel retort and a pair of oppositelyinclined grates one along each of the lateral sides'of the retort, theretort'di'scharging laterally over such sides upon such grates, eachgrate composed of inclined grate bars having stepped fuel supportingtopsides, and loosely inter-' fitting to afford numerousnarrow and non-.

1 sifting air passa es delivering into the fuel signatures hereto.

bed, twyer members resting on the retort sides, and a series of separateremovable cap pieces. overlying the tops of the twyer members andalternate grate bars and having underneath interlocking engagement withthe top edges of both the twyer members and such alternate grate bars,and means for reciprocating the remaining grate bars.

In witness whereof, we have aflixed our ERNEST B. PRIEBE- DANIEL P.MINER.

